You can now set up your Description as well as your Keywords for Partner Websites. These are both useful mechanisms for improving your Search Engine Optimization. The setup is in your Partner Dashboard under Website -> Setup.
You can put a number of keywords, but the more keywords, the lower value Google will place on them. So try to figure out what your customers might be searching for. Google has lowered the value of Keywords in doing their search ranking algorithms, but they are still useful:
The Website Description is actually more useful. Google scores this much higher than the keywords. Most importantly, it is what Google will place under your Website name as a description. This is limited to 155 characters.
